Apron lift mechanism



May 10, 1960 H. w. RocKwELL APRON LIFT MECHANISM 3 Sheets-Sheet 1 Filed April 29, 1958 May 10, 1960 H. w. RocKwELL APRoN LIFT MECHANISM 3 Sheets-Sheet 2 Filed April 29, 1958 www@ 67X). @fac/bwa /ff MKM May 10, 1960 H. w. ROCKWELL APRoN LIFT MECHANISM 3 Sheets-Sheet 5 Filed April 29, 1958 MN ww. @@-L mmlj EM HUMIWANMN l I L u Q @JQ Em@ MN 3N \w mw MN lig l APRGN LIFT MECHANISM This invention relates to earth movers and more particularly to an earth mover having an improved interrelation between the apron, the ejector and the main bowl.

In this type of device there is provided a wheel supported main earth containing bowl substantially closed at one end by an ejector. The ejector is movable through the bowl in a forward direction to discharge earth from the bowl over a leading cutting edge. Also, there is provided a front apron movable from a lower position completing the front end closure of the bowl and restraining emth therein, to an upper or open position in whichl the apron is spaced a substantial distance from the cutting edge of the bowl. In the open position the front apron affords a relatively large opening through which earth can spill from the front apron and through which earth contained in the main bowl can be expelled from the machine. Y

This vehicle is used for excavating earth and transporting the excavated earth to dilferent locations. VHeretofore it has been common practice to increase the width of the scraper unit to provide industry with a larger earth mover that will move more earth during a given period of time. This method has not proven entirely satisfactory because most States have imposed a limitation on the width of the vehicles traveling on V'their highways. Therefore, it is desirable to increase the length of the scraper unit to provide industry with an earth mover having a greater load carrying capacity.

Previously designed earth movers such as shown in the patent to L. L. Hyler, 2,565,850, Apron and Ejector Control for Earth Moving Apparatus, are restricted in lengthening the scraper unit. In the patent to Hyler, 2,565,850, the apron is pivotally connected to a rigid portion extending forwardly from the main body of the ejector. Also as shown, restraining links and apron arms form an overcenter toggle restricting any substantial movement of the ejector while the apron is in its closed position and when moved from an overcenter locked position the ejector begins its travel through the bowl and forces the apron to pivot about its axis to an open position. ln moving through the bowl the ejector is supported by a pair of rollers which also support the pivotally attached` apron arms. The apron and ejector are carried on the same rollers which limits the position of the apron pivot axis to a location near the ejector. In order to lengthen the scraper it becomes necessary to replace the standard size apron with a longer specially an earth mover in which the ejector, the apron and the main bowl have an improved interrelation.

Itis a further object of this invention to provide an interconnected apron and ejector which are separately supported.

It is a further object of this invention to provide an interconnected apron and ejector which permits the lengthening of the main bowl without disturbing the interrelation between the restraining link and apron.

It is a further object of this invention to provide greater forward movement of the ejector in relation vto the forward movement of the apron arm pivot axis.

lt is a further object of this invention to provide an interconnected apron and ejector of the hereinbefore outlined character wherein the vertical swinging movement ot the apron is limited to an arcuate path that will not interfere with the ejectors forward movement.

It is a further object of this invention to provide a double overcenter toggle which provides no substantial movement of the ejector during the initial opening of the apron.

These and other objects and advantages of this invention will be evident when the following description is read in conjunction with the vaccompanying drawings, in which:

Fig. 1 is a side view of the scraper unit of an earth mover with the apronv in its closed position;

Fig. 2 is a sectional view cut at line II-II showing the roller connection to the ejector, the track for mounting the roller, and the' link connection to the ejector;

Fig. 3 is a sectional view cut at line III-lil showing the roller connection to the apron arm and the track for mounting the roller;

Fig. 4 is a side view of the scraper unit of an earth mover with the apron in an opened position;

Fig. 5 is a side view of the scraper unit of au earth mover showing the apron in a further opened position; i

Fig. 6 is a side view of the scraper unit of an earth mover showing the apron inY its upper position andthe ejector in its forward position; and

Fig. 7 is a top View vof the scraper unit shown in Fig. 1. A

Referring to Figs. 1 and 7, this invention is embodied in a scraper unit of an earth mover which includes a main. bowl frame 8 with a bottom 9 and a pair of support wheels 1S. A yoke having a pair of side arms 171 is pivotally connected by pivot pins 12 to side walls 13 of bowl frame 8. The yoke lll of the scraper unit connects the bowl frame 8 to a suitable tractor unit, not shown. y

To produce relative motion between the bowl frame and the yoke there is provided a pair of doubler acting hydraulic jacks i6. The jacks 16 are hydraulically in parallel and serve to raise and lower the cutting edge 17 to position the scraper bowl in the earth excavating position, or in an earth transporting position.

To assist in handling the excavated earth, the earth mover includes an ejector 2G having a rearwardly extended channel stem 2 `movable between a rearward loading position, wherein it constitutes a wall closing the rearward end of the bowl, and a forward positionedjacent to cutting edge 17. The forward motion ot the ejector ejects earth from the bowl.

Referring also to Fig. 2, Ythe ejector is connected to a pair of guide elements illustrated as rollers 22 by pivot pins Z3. The rollers are mounted in guide menibers illustrated as tracks 24 formed in the side walls of the main bowl. As the ejector is ymoved forwardly or rearwardly, the rollers 22 move along tracks 24 which guide and support the ejectors movement through the bowl.

The channel beam stem 21 is provided with stabilizing rollers 25 preferably three in number. These rollers engage the three surfaces of a longitudinal triangular section beam 26 in a conventional manner. To produce forward movement of the ejector, a pair of three stage single acting hydraulic jacks 27 is provided. The jacks are connected at their forward ends by pins 28 to bracket 29 extending from the ejector 20 and at their other ends by pins 30 to bracket 31 of the bowl frame 8.

An apron 35 is provided which moves between a lower position adjacent the cutting edge 17, wherein it closes the otherwise open forward end of the bowl frame S and an upper position away from the cutting edge wherein the bowl is open at the forward end. Referring also to Fig. 3, the apron includes a pair of rearwardly extending arms 36 which are connected to a pair of guide elements illustrated as rollers 37 by pivot pins 38 to pivot about axis 38'. The rollers are mounted in tracks 24 formed in side walls 13. As the apron is moved to its upper position about axis 38', the rollers 37 move along tracks 24. The tracks 24 guide and support the movement of the apron arm as the apron travels to its upper position. The apron arms are extended beyond pivot pins 38 and are curved upward forming an extended portion 40. The extended portions 40 of the apron arms provide a mounting structure for a pair of connecting links 39.

Referring also to Fig. 5, corresponding ends of links 39 are connected to the extended portion 40 by pivot pins 41, and the opposite ends of links 39 are connected to the ejector 2G by pivot pins 42. To complete the linkage a pair of restraining links 44 are connected to the side walls 13 of the bowl frame 8 by pivot pins 45 and are connected to a bracket 46 on the apron arms by pivot pins 47. The apron arms 36 and links 39 form an overcenter toggle when the axis 41 of pivot pins 41 lies above an imaginary line 32 between the axis 3S of pivot pins 38 and axis 42 of pins 42. The links 44 and apron arms 36 form an overcenter toggle when the axis 47' lies below an imaginary line 33 between the axis 38 and the axis 45'.

To produce movement of the apron about the axis 38 a hydraulic jack 48 is provided. The jack 48 is shown in Figs. l, 4, and 6 in an upright position for illustrative purposes. A cable 50 is connected to anY eye 52 on the apron, passes over a pulley 53 mounted on the outer end of the piston rod 54 and extends to a suitable tie down on the yoke frame.

The operation of the apron ejector linkage is illustrated in Figs. l, 4, 5 and 6. Referring to Figs. l and 7, there is shown a hydraulic control circuit including a valve 55 and conduit 56. The inlet 57 of the apron jack 48 is connected by conduit 56 to the inlets 58 and 58' of the ejector jacks 27 so that they act to lift the apron and move the ejector forwardly in predetermined motion defined by the apron ejector linkage. In operating the apron, pressure fluid is allowed to flow through conduit 56, causing jack 48 to expand and not only is lifting force exerted on the apron but likewise a forward force is exerted on the ejector by jacks 27. The two toggles described above cooperate to oppose any forward movement of the ejector.

Referring now to Fig. 4, jack 48 is expanded to rotate the apron upward about its pivot axis 38 to the excavating position without breaking the two toggles. Accordingly, the apron may be raised suiciently to permit excavating without appreciable forward movement of the ejector. As shown in Fig. 4, the apron is in an opened position, the toggles are both in a dead center position and the bowl is in the load carrying position. The bowl may be lowered to the excavating position for excavating earth. In the excavating position the apron is opened to allow the excavated earth into the bowl, with the opening approximately the same as shown in Fig. 4. With the bowl in the excavated position the toggles are also in a dead center position restraining any forward movement of the ejector.

Referring to Fig. 5, the apron has been raised a sufiicient amount to break both toggles simultaneously, and jacks 27 are effective to move the ejector forward. As the ejector is moved forwardly on rollers 22, tracks 24 guide the movement of the ejector through the bowl. At this point of the operation the cable 50 slacks and the jack 27 continues to move the apron forwardly on rollers 37 and upwardly through the action of links 39, and pivot pins 47 are forced upwardly through an arcuate path about axis 45. Thus the restraining link 44 and the guiding action of roller 37 in track 24 establishes the path of vertical swinging movement of apron 35.

The extension 40 of the apron arm 36 moves from a rearwardly disposed position (as shown in Fig. l) to a downwardly disposed position (as shown in Fig. 6) during ejection thereby permitting the ejector to move a greater distance per degree of upward pivoting of the apron than has previously been possible where the apron and ejector are carried on the same roller.

As shown in Fig. 6, the forward movement of the ejector and upward movement of the apron have been completed. The cable Si) is slack, the apron is in its extreme upper position, completely opening the forward end of the bowl, and the ejector is in the forward position having completely ejected the excavated material.

When the force on the ejector is removed, conventional ejector return springs, such as shown in U.S. patent to L. L. Hyler 2,565,850 cause the ejector and apron to retrace through the path of motion previously described in reverse sequence. The weight of the apron assists in returning the apron and ejector to their original positions respectively.

In accordance with my invention the interconnected linkage allows no substantial movement of the ejector during the initial opening of the apron. During the movement of the apron and ejector a substantial portion of the weight of the apron and the ejector is carried by separate rollers permitting the use of standard size rollers rather than the very large special type rollers required when the apron and ejector are supported on the same rollers. The use of separate rollers for supporting the apron and ejector also permits the apron pivot axis to be located at a point away from the ejector rather than the restricted position near the ejector. Also the rollers 37 are positioned on the apron arms 36 at a point spaced from the axis of pin 41 permitting the apron arms to travel forwardly less distance than the ejector, thereby permitting the ejector greater reciprocating movement within the bowl than heretofore provided. The net result is an improved interconnection between the bowl, the ejector and the apron which allows a longer main bowl for increasing the load capacity of the earth mover without increasing the size of the restraining link 44 or disturbing its interrelation with the apron.

While only one particular embodiment of the applicants invention has been described herein, it should be understood that the applicants invention is not restricted thereto and that it is intended to cover all modifications of the invention which would be apparent to one skilled in the art and that come within the scope of the appended claims.

What is claimed is:

l. An earth mover comprising: a bowl having laterally opposite side walls; a guiding member secured to one of said walls; a rst guide element guided by said guiding member; an ejector connected to said first guide element for longitudinal reciprocating movement within said bowl; a second guide element in contact with and guided by said guiding member and being positioned forward of said first guide element; an apron having a rearwardly extending arm connected to said second guide element for vertical swinging movement relative to said bowl; a first link having its opposite ends pivotally connected, respectively, to said arm and ejector; and a second link having its opposite ends pivotally connected, respectively, to said arm and bowl.

2. The structure set forth in claim 1 wherein said guiding member is a track and said guide elements are rollers.

a3. An earth mover comprising: a bowlhaving laterally opposite side walls; a guiding member secured to one of said walls; a iirst guide element guided by said guiding member; an ejector connected by a irst pivot to said first guide element for longitudinal reciprocating movement within said bowl between loading and ejected positions; a second guide element in contact with and guided by said guiding member and being positioned forward of said first guide element; an apron having a rearwardly extending arm connected by a second pivot to said second guide element; a first link having its opposite ends connected by a third pivot to said arm and by a fourth pivot to said ejector; and a second link having its opposite ends connected by a fifth pivot to said arm and by a sixth pivot to said one of said side walls.

4. The structure set forth in claim 3 wherein said guiding member is a track, and said guide elements are rollers.

5. The structure set forth in claim 3 wherein said third pivot is positioned betweenl said rst and second pivots, and said fth pvot is positioned forward of said second pivot. l

6. An earth mover comprising: a bowl having laterally opposite side walls; a guiding member secured to one of Vsaid walls; a iirst guide element guided by said guiding member; an ejector connected to said iirst guide element member and positioned forward of said rst guide element; an apron having a rearwardly extending arm pivotally connected to said second guide element for vertical swinging movement relative to said bowl between closed and open positions, said arm having a portion extending rearwardly of the pivot connection of said arm and second guide element; a first link having its opposite ends pivotally connected to said portion and ejector; and a second link having its opposite ends pivotally connected to said arm and bowl, said second link and second guide element forming an overcenter toggle for restraining the forward movement of said ejector when said apron is in said closed position. Y,

7. An earth mover comprising: a bowl having laterally opposite side walls; a guiding member secured to one of said walls; a first guide element guided by said guiding member; an ejector connected by a first pivot to said first guide element for longitudinal reciprocating movement within said bowl; a second guide element guided by said guiding member and positioned forwardly of said rs't guide element; an apron having a rearwardly extending arm pivotally connected by a second pivot to said second guide element for vertical swinging movement relative to said bowl between closed and open positions, said arm having a portion extending rearwardly of said second pivot; a connecting link having one of its opposite ends connected by a third pivot to said portion and the other of its opposite ends connected by a fourth pivot to said ejector; and a restraining link connected by a fifth pivot to said arm forward of said second pivot and by a sixth pivot to said bowl, said second, third and fourth pivots forming an overcenter toggle between said apron and ejector and said second, iifth and sixth pivots forming an overcenter toggle between said apron and bowl, said toggles restraining the forward movement of said ejector l Y when said apron is in said closed position.

8. An earth mover comprising: a bowl having laterally opposite side walls; a guiding member secured to one of said walls; a first guide element guided by said guiding member; an ejector connected by a first pivot to said first guide element for longitudinal reciprocating movement within said bowl; a second guide element guided by said guiding member and positioned forward of said rst guide element; an apron having a rearwardly extending aim pivotally connected by a second pivot to said second guide element for vertical swinging movement relative to said bowl between the closed and open positions, said arm having a portion extending rearwardly of said second pivot; a connecting link having `one of its opposite ends connected by a third pivot to said portion and the other of its opposite ends connected by a fourth pivot to said ejector; and a restraining link connected by a fifth pivot to said arm forward of said second pivot, and by a sixth pivot to said bowl; said second, third and fourth pivots forming an overcenter toggle between said apron and ejector, and said second, fifth and sixth pivots forming an overcenter toggle between said apron and bowl, said toggles being in a dead center condition when the apron swings upwardly a predetermined amount, and said toggles being simultaneously broken as the apron continues its upward swing to said open position.

9. The structure set forth in claim 8 wherein said guiding member is a track and said guide elements are rollers.

References Cited in the le of this patent UNITED STATES PATENTS 2,275,601 Austin et al Mar. l0, 1942 2,394,428 Cox Feb. 5, 1946 2,565,499 Hyler Aug. 28, 19,51 

